While there, he will promote what he is calling "economic freedom zones," which he says are similar to Jack Kemp's "enterprise zones" of the 1990s.

"This is enterprise zones on steroids," Paul told Hannity.

Paul's plan would lower personal and corporate tax rates to 5 percent and get rid of the capital gains tax. It also would lower payroll taxes for workers and employers and "cut red tape." Immigrants would be offered $50,000 to move into cities, and entrepreneurs would also be invited in.

The Democratic Party method for half a century has been to bail out cities and institutions with stimulus programs, which haven't worked, Paul said. His plan doesn't pick the winners and losers, he said, "but the consumer does."

"It's phenomenal how much money can be left in Detroit simply by lowering the taxes in Detroit," he said.

Paul, thought to be a presidential candidate for 2016, said the GOP needs to compete for votes in big cities, and his plan would show that Republicans care about urban areas at times other than right before an election.

"But it's also good for America to have big cities like Detroit that were once industrial engines — we need them thriving again," he said.